We propose to study the enzyme system concerned with the biosynthesis and oxidative decarboxylation of alpha-hydroxy fatty acids and related pathways. During the past several years we demonstrated and partially characterized, for the first time, the enzyme system which synthesizes brain cerebronic acid (alpha-hydroxylignoceric acid) and other alpha-hydroxy fatty acids from lignoceric acid (tetracosanoic acid) and other nonhydroxy acids. We have shown that the enzymic activity which replaces the (Pro-2R)-hydrogen of fatty acids with an hydroxyl group, requires microsomes, heat-stable, and heat-labile factors, and that alpha-hydroxylation appears to be a rate-limiting step in the synthesis of cerebroside containing alpha-hydroxy fatty acid. We propose to characterize further the alpha-hydroxylation system. Specifically, we plan to purify and charcterize the above two water-soluble factors, solubilize and characterize the microsome activity and to identify an electron donor of this reaction. We have obtained evidence that lignoceric acid linked to large molecular compound through a thioester bond may be an intermediate of lignoceric acid alpha-hydroxylation. We propose to isolate and fully characterize this compound. The control mechanism of alpha-hydroxylation will be further studied using oligodendroglial cell culture and various compounds which affect spingolipid metabolism. Studies of the oxidative decarboxylation of alpha-hydroxy acids and of the beta-hydroxylation and beta-oxidation of lignoceric acid are also planned.